Poor quality filter cakes, low machine pressure and fluid leaks; these are all common dewatering maintenance issues to be aware of. Some of these issues will require the attention of a manufacturer's representative, but often times they are quick fixes. Add these tips to your maintenance routine to keep your filter presses running at optimal performance.
1. Press is not creating good filter cakes
This can be a sign that the filter cloths are in need of a good, thorough cleaning. There are a few ways to clean filter cloths:
Scrape the surface of the cloth using a spatula (We have spatulas made for just this purpose! If you need one, give us a call at (616) 772-9011.
Recirculation cleaning, which circulates acid, caustic, or cleaning solution through the press to dissolve the particulate build up
Recirculation cleaning is the most effective method for cleaning filter cloths.
If cleaning the filter cloths doesn't improve the quality of your filter cakes, it might be time to replace them. The videos below from Evoqua's own Dr. D show the proper way to change filter cloths on both gasketed and non-gasketed filter plates.
2. Filter press is leaking
Is your 470mm filter press leaking around the locknut or your 630mm or larger press leaking from the bottom leg drain holes at the beginning of the feed process?
There might be a problem with the center feed pipe, the most common issue being the center quad ring is not sealed properly. To fix the leak you will need to:
Open the press and shift all the plates into an open position
Use a spanner wrench or pliers to remove the clip that holds the filter cloth on the clip nut seat
For non-gasketed plates - lift the cloth off the top cloth pins. For gasketed plates - peel down the top 2/3 of the cloth so the feed pipe can be moved
Loosen the locknut and push the feed pipe out so you can reinstall the quad seal (may require a few drops of super glue)
Reinstall the liner pipe and tighten the locknut
Reinstall the filter cloth
3. Press won't build/hold hydraulic pressure
Having the right amount of pressure is key to a properly functioning filter press. If your press is not pushing water and sediment through at the appropriate level, one of these things is happening:
The check valve is clogged
Remove the end of the valve
Remove and debris or obstructions
Check the O-rings for wear
There is an improperly set relief valve
Remove the valve
Check the O-rings for wear
Make sure that no debris is forcing the valve open
The OPEN/CLOSE/PUMP switch is bad.
With the air supply "OFF", remove the Blue Line from the back of the Selector Switch
Turn switch to "PUMP"
Turn air supply "ON", and if air continues to leak out the switch needs to be replaced
4. Press needs an oil change
The hydraulic oil in filter presses should be changed once a year or every 2,000 operating hours, oil filters should also be changed at this time. Routine oil changes keep filter presses running smoothly and efficiently.
In the video below Dr. D walks through the process of changing the oil in a small J-Press® filter press.
5. Press is leaking hydraulic oil
As with any piece of machinery, filter presses can have oil leaks. There are 2 primary reasons why your filter press is leaking hydraulic oil:
The hydraulic reservoir has been overfilled.
Take a look at the reservoir's sight gauge when the cylinder is extended
Add or remove oil until the appropriate levels are reached
There is a problem with your hydraulic cylinder, in which case you will need to contact your customer service representative.